The present invention relates to an apparatus, such as, a sprinkler for fluctuating or changing the velocity of fluid flowing out from a nozzle at a specific cycle or period, for example.
In general, for the purpose of changing the velocity of fluid flowing out from a nozzle, the velocity is controlled by changing the configuration of the flow passage in the vicinity of the nozzle, there by changing an orbit of the fluid jetting out from the nozzle. In particular, as the structure for controlling the fluid, without using an electric driving mechanism, etc., a mechanism is used, such as, a nozzle for use of a jet bath (see Patent Document 1) or a pulse air jet generating device (see Patent Document 2), for example.
Each of those comprises a mechanism to be driven through hydraulic power in the vicinity of the position of flow-out in the nozzle, where in the configuration of the flow passage is changed through movement of the mechanism with an aid of function of the hydraulic power; i.e., a mechanism for controlling the velocity by changing the orbit of fluid.
Other than this, there is already known a means, such as, a flip-flop nozzle (see Non-Patent Document 1), in which the velocity of fluid can be varies without changing the configuration of flow passages.
In this, a moving direction of fluid is changed with using a pressure difference caused by the fluid jetting out from the nozzle portion. With applying the structure of switching over the pressure difference due to the change in the moving direction of fluid, the moving direction of fluid is changed, and repetition of this enables to change or oscillate the flow velocity at a specific period.
Patent Document 1
Japanese Patent Laying-Open No. 2001-62354(2001), “NOZZLE DEVICE FOR JET BATH USING NOZZLE DEVICE”, pp 9-11;
Patent Document 2
Japanese Patent Laying-Open No. Hei 10-52654 (1998), “PULSE AIR JET GENERATING DEVICE”, p 9; and
Non-Patent Document 1
32nd Fluid Dynamics Lecture Meeting by Aerospace Institute and Fluid Dynamics Institute, “Self-Induced Oscillation of a Jet Issued from a Flip-Flop Jet Nozzle”.
However, if trying to change the flow velocity by changing the configuration of flow passage, as is taught in the Patent Documents 1 and 2 mentioned above, there are following problems can be listed up:
First, because a portion of energy that the fluid has is used as energy for driving the mechanism, therefore a loss of energy is increased, thereby lowering the flow velocity;
Second, due to movement of the mechanism, there is a possibility of generating dusts, in particular, from the bearing thereof, etc., thereby contaminating the fluid, therefore it is difficult to apply it into a facility for producing drags, foods, or into a clean room of high cleanness, etc.;
Third, maintenance is indispensable for the mechanism;
Fourth, a number of parts of the nozzle is increased for building up the mechanism, and also costs rise up due to the complicated manufacturing steps thereof; and
Fifth, due to the problems, i.e., durability of the mechanism portion or the like, such as the bearing, etc., it is difficult to be applied into the conditions, such as, a fluid of high temperature or low temperature, a fluid of strong acid or strong alkaline, also into a gas contaminated with dusts and a water of rivers containing waste therein; i.e., it is restricted on the fluid to which the device can be applied.
On the contrary to this, with an example of the Non-Patent Document 1, since no movable mechanism is provided therein, there occurs no such the problem as mentioned in the above. However, because of the principle that a flow is generated within a connector duct by using the pressure difference generated in the nozzle portion, as driving force thereof, thereby reversing the pressure difference, there is a necessity of a certain amount of flow. Namely, for producing the flow amount with a little pressure difference, it is necessary to lower the flow resistance within the connector duct, and then the connector duct increases in the area of flow passage therein, therefore there is a problem that the device or apparatus comes to be large in the sizes, as a whole.